20 octubre 2014
Physicists have built a tractor beam that can repel and attract objects, using a hollow laser beam, bright around the edges and dark in its center. It is the first long-distance optical tractor beam, 100 times larger than previous ones.
http://feeds.sciencedaily.com/~r/sciencedaily/~3/htBqIdeY9xc/141020105043.htm
